Radiation Therapy in Pets

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Radiation Hair Loss Mastiff

Perhaps you are aware that radiation therapy is an option for some types of cancers in pets, but did you know that radiation therapy can also greatly improve quality of life when an outright cure is not an option? In this article we will discuss what exactly radiation therapy is, what its risks are, and examine the dual roles that radiation therapy plays in our pets with cancer.

How Radiation Therapy Works

When it is used at thousands of times the amount to produce a chest radiograph, radiation can kill cells by damaging their DNA. While it is true that both normal cells and cancer cells are affected, radiation treatment is designed to maximize its effects on tumors while minimizing normal tissue damage.

Radiation Risks and Side Effects

Radiation therapy requires multiple treatments with general anesthesia because the pet must remain entirely still for the procedure. The risks of general anesthesia are higher if the pet is experiencing disease or cancer of the lungs, liver, heart, or kidneys. The presence of lung metastases is not a contraindication to palliative radiation treatment, as long as the pet is not showing clinical signs related to metastatic disease. The treatments only take a few minutes, so the patient is under anesthesia for a short amount of time and most patients are able to return home the same day.

Most side effects are not serious and are typically related to the area being treated. Side effects depend upon which region of the body is treated, but may include a skin reaction similar to a sunburn, hair loss, and pigmentation change. Diarrhea and lethargy may also occur. Not all animals develop side effects, but when they do, they are usually quick to return to their normal self.

Dual Roles

There are two approaches used with radiation therapy—curative and palliative. If the desire is to control the tumor long term and achieve a cure, a much more intense protocol is used. This is referred to as radiation therapy with a curative intent. Depending on the tumor’s location within the body, most patients treated with curative intent protocols are treated over a period of several weeks.

Alternatively, sometimes radiation is administered to relieve the patient of pain and/or improve regional function. This is referred to as palliative radiation therapy. Palliative radiation therapy is a much less intense protocol, mainly because it is treatment aimed at maintaining a high quality of life for the pet when, for whatever reason, long-term cancer control or a cure are not an option. This type of radiation therapy is most often used to control pain. Unfortunately, the duration of patient response is far shorter than patients treated with more aggressive (curative) protocols, but it is still a great option when pet parents have weighed the risks and benefits and chosen the palliative approach.

Veterinary Opinion

Regardless of whether radiation therapy is curative or palliative, most pets do extremely well with it if an appropriate workup is done beforehand to confirm no other disease is present that would make radiation therapy a poor choice. Though the costs of radiation therapy may keep it from being widely-utilized in the veterinary industry, partly due to the need for general anesthesia for each treatment session, most pet parents who pursue this route of treatment are very pleased with their decision to do so.